Process of extracting copper with certain substituted 2-hydroxybenzophenoximes

ABSTRACT

Certain 2-hydroxy benzophenoximes containing an electron withdrawing substituent(s). Compositions comprised of such benzophenoximes and certain Alpha -hydroxy aliphatic oximes. Compounds and compositions are useful for the extraction of metal values.

United States Patent Mattison et a1.

[15] 3,655,347 [451 Apr.l1, 1972 [54] PROCESS OF EXTRACTING COPPER WITH CERTAIN SUBSTITUTED 2- HYDROXYBENZOPHENOXIMES [72] Inventors: Philip L. Mattison, New Brighton; Ronald R. Swanson, New Hope, both of Minn.

[73] Assignee: General Mills, Inc.

[22] Filed: Aug. 12, 1970 [21] Appl. No.: 63,279

Related US. Application Data [62] Division of Ser. No. 714,040, Mar. 18, 1968.

3,055,754 9/1962 Fletcher ..23/312 3,088,799 5/1963 Fetscher ..23/312 3,197,274 7/1965 White ..23/312 3,224,873 12/1965 Swanson ..23/312 3,284,501 11/1966 Swanson.... .....260/566 3,294,842 12/ 1 966 Swanson ..260/566 3,428,449 2/1969 Swanson ..23/312 OTHER PUBLICATIONS Morrison and Boyd, Organic Chemistry, 1959, pages 291 to 297.

Primary Examiner-Norman Yudkoff Assistant Examiner-S. J. Emery Attorney-Anthony A. Juettner and Gene 0. Enockson [57] ABSTRACT Certain 2-hydroxy benzophenoximes containing an electron withdrawing substituent(s). Compositions comprised of such benzophenoximes and certain a-hydroxy aliphatic oximes. Compounds and compositions are useful for the extraction of metal values.

14 Claims, No Drawings PROCESS OF EXTRACTING COPPER WITH CERTAIN SUBSTITUTED Z-HYDROXYBENZOPHENOXIMES This application is a division of our earlier application Ser. No. 714,040, filed Mar. 18, 1968.

The present invention relates to the process of extracting copper values from aqueous solutions thereof using certain substituted 2-hydroxybenzophenoximes.

it has recently been discovered that copper values can be recovered economically from certain aqueous leach liquors using a liquid ion exchange process employing particular phenolic oximes as the reactants. In this regard, percolation of water, with or without acid present, through waste dumps of low-grade copper containing rock yields dilute copper containing solutions, normally of copper sulfate. Such dilute copper sulfate liquors are usually close to pH 1.9-2.5 and contain relatively large amounts of ferric and ferrous iron relative to the copper. The phenolic oximes dissolved in an essentially water-immiscible organic solvent preferentially extract the copper values into the organic phase. Such values can then be stripped from the organic phase and recovered from the resulting concentrated strip solutions such as by electrolysis.

The phenolic oximes used prior to the present invention were those having the basic structure:

where R and R are saturated aliphatic, ethylenically unsaturated aliphatic or saturated or ethylenically unsaturated aliphatic ether groups (i.e.--OR") and m and n are 0, 1, 2, 3 or 4. The said phenolic oximes contain three to 25 carbon atoms in the R and R groups, the latter being of one to 25 carbon atoms when saturated and three to 25 carbon atoms when ethylenically unsaturated.

While the above phenolic oximes were found to be effective as copper extractants over a wide pH range, their extraction efficiency drops off considerably when the aqueous copper containing solutions have pHs below about 1.5 and especially below about 10. Since certain leach liquors have very low pHs or develop low pHs on being subjected to liquid ion exchange extraction, it was considered to be a very desirable object to provide an extractant or extractants which would function with increased efficiency on such solutions. Certain concentrated copper solutions of very low pH are obtained by treatment of copper oxide ores with relatively strong acid leaching solutions. Further, in the ordinary extraction processes, hydrogen ions are exchanged for copper ions with the result that as extraction proceeds, the aqueous phase becomes more and more acidic. Consequently, for concen trated copper solutions, an extractant which is effective at very low pH ranges is needed.

We have now discovered a new group of compounds which are unexpectedly effective extractants for copper values from aqueous solutions thereof of low pH. These compounds generally have the formula as described above for the recently discovered phenolic oximes but in addition, have one or more electron withdrawing substituents on the ring containing the phenolic hydroxyl group, such electron withdrawing substituents substantially increasing the efiiciency of the oxime compound as a copper extractant from low pH aqueous solutionsi.e. leach liquors. Our new compounds have the following structural formula:

where R and R are defined above, E is an electron withdrawing substituent, p is l, 2, 3 or 4, m is or a whole integer up to 4-p and n is 0, l, 2, 3 or 4. The electron withdrawing capacity of any particular substituent is proportional to the acid ionization constant of the corresponding phenol containing only such substituent. Phenol, itself, has an acid ionization constant Ka, of about 1.1 X l0 as variously reported in the literature (See Organic Chemistry," 1959, by Robert Thornton Morrison and Robert Neilson Boyd, page 586). As such the substituents useful in our new compounds, provide substituted phenols with acid ionization constants of about 50 X 10 and higher. In this regard, chloro in the para position yields a phenol having an acid ionization constant of only 6.3 X 10 whereas orthochloro phenol has a Ka value of 77 X 10". Accordingly, benzophenoximes substituted with a single chlorine in the para position to the hydroxyl group have essentially the same extraction efficiency as the corresponding unsubstituted compounds, and thus such chloro substituent can be considered as inert. The di and higher halogen substituted phenols have Ka values considerably above 50 X 10"". A preferred substituent is the nitro group, and especially good results are obtained when the said group is in the ortho or para position. Polynitro substituted phenols have high Ka values. Other representative useful electron withdrawing substituents are Cn, SF SO R and the like where R is an organic radical such as an alkyl radical of one to eight carbon atoms. The electron withdrawing group should not adversely affect the solubility or stability of the benzophenoxime and should not sterically hinder the OH group or cause interfering side reactions. Thus the reasonably bulky SF group would not be in the ortho position since it would sterically hinder the OH group. Likewise, the NH group in the meta position yields a substituted phenol having a Ka value of 69 X 10 However, such group would interfere in the extraction process by complexing or reacting with the acid of the low pH copper containing solution.

The compounds of the present invention can be prepared by a number of methods. These routes involve the formation of the benzophenone followed by conversion of the benzophenone to the benzophenoxime, with the electron withdrawing substituents being introduced via starting materials or after formation of the benzophenone. Two illustrative methods of making the benzophenones include the following. The first such method is that reported by Newman (J. Org. Chem, 19, 985l,002, 1954). This method involves the reaction of a phenol with a benzotrichloride in accordance with the following equation:

A second method involves the rearrangement where a phenolic ester is rearranged to a benzophenone in accordance with the following equation:

A third preferred method of producing the benzophenones is illustrated in the following sequence:

COClz or SOCl The starting phenol, benzotrichloride and the like in the above procedures may contain various radicals as R and R. Representative of saturated radicals are methyl, ethyl, dimethylethyl, sec-butyl, tert-butyl, octyl, nonyl, decyl, dodecyl and the like. Branched chain alkyl groups are preferred over the straight chain groups. Various ethylenically unsaturated groups can also be used as R and R and the same may be branched or straight chain. Representative of such groups are pentenyl, hexenyl, octenyl, dodecenyl, octadecenyl and the like. It is preferred that such groups contain less than about two double bonds and more preferably a single double bond. The R" portion of the ether groups can be the saturated and ethylenically unsaturated aliphatic groups as described above. The R" portion of the said ether groups is preferably an alkyl group. In addition, the saturated, ethylenically unsaturated and ether groups may contain inert substituents such as halogen, ester, amide and the like. The non-hydroxyl substituted aromatic nucleus of the benzophenoximes may also contain inert substituents. By inert is meant that the said substituents do not affect the solubility, stability or extraction efficiency of the compounds to any significant extent. Representative of aliphatic radicals containing inert substituents are cmot zn' 0 and the like where R' and R"" are alkyl groups of one to about eight carbons for example.

lo the above procedures, the electron withdrawing substituent may be introduced into the compound from the starting phenol. And as indicated the same can advantageously be introduced after the benzophenone is prepared. This latter method is preferred in preparing our compounds wherein the electron withdrawing group is the nitro group. Thus the corresponding benzophenone can be dissolved in a suitable solvent such as a mixture of acetic acid and acetic anhydride and fuming nitric acid added to cause nitration of the benzophenone.

The benzophenoximes of the present invention are prepared from the described benzophenones by reaction of the latter with a hydroxyl amine salt under reflux conditions. Such reaction can be carried out by refluxing the reactants in an alcohol such as methanol or ethanol and adding pyridine or sodium acetate to combine with the acid associated with the hydroxylamine.

As indicated, our new compounds are efficacious extractants for copper values having unexpected extraction efficiency under low pH conditions. In the process which also forms part of the present invention, the substituted benzophenoximes are dissolved in an essentially water-immiscible organic solvent which is contacted with the aqueous copper containing solution. A complex is formed between the copper values and the substituted benzophenoxime. Such complex is soluble in the organic solvent and thus the copper values are preferentially extracted into the said solvent. The organic phase is then separated from the aqueous phase and the copper values are stripped from the organic phase, usually by means of an acid. The organic phase containing the regenerated substituted benzophenoxime can be reused, such as by recycling, to contact further quantities of copper containing aqueous solutions. The copper values can be recovered as copper metal from the strip solution by electrolysis, for example.

The water-immiscible organic solvents preferably employed in our process are the aliphatic hydrocarbon solvents such as the petroleum-derived liquid hydrocarbons, either straight or branched chain, such as kerosene, fuel oil etc. Various aromatic solvents may also be used, such as benzene, toluene, xylene and others, for example, those derived from petroleum processing which may contain alkyl substituted aromatic materials. Typical of the latter solvents are those sold under the Panasol trademark by Amoco Chemicals Corporation, both in the RX and the AN series. These solvents are liquid and essentially insoluble in water. Generally, all these hydrocarbon solvents have specific gravities in the range of 0.65-0.95 and have a midboiling point in the approximate range of l20--6l5F. (ASTM Distillation). In addition to the simple hydrocarbon solvents, the chlorinated hydrocarbons may also be used and in some instances may improve solubility. Accordingly, both the unsubstituted and the chlorinated solvents are contemplated by the term liquid hydrocarbon.

The substituted benzophenoximes of the present invention are further characterized as having sufficient solubility in one or more of the above solvents or mixtures thereof to make about a 2 percent by weight solution and as being essentially insoluble or immiscible with water. At the same time, the benzophenoxime should form a complex with the copper, which complex, likewise, is soluble in the essentially water-immiscible organic solvent to at least the extent of about 2 percent by weight. These characteristics are achieved by having alkyl, ethylenically unsaturated aliphatic or ether substituents as described on either ring. It is necessary to have substituents which total at least three carbon atoms. Usually, it is preferred not to have more than 25 carbon atoms total in the substituents since these substituents contribute to the molecular weight of the oxime without improving operability. Large substituents, therefore, increase the amount of oxime for a given copper loading capacity. In general, the branched chain alkyl substituents effect a greater degree of solubility of the reagent and of the copper complex and, accordingly, these are preferred. The compounds of the present invention are preferably used in an amount of about 2 to 50 percent by weight and more preferably about 5 to 15 percent by weight based on the weight of the organic phase.

The following examples illustrate preferred embodiments of the present invention without being limited thereto. Unless otherwise indicated, all parts and percentages are by weight.

EXAMPLE I 2-l-lydroxy-3-nitro-5-dodecylml. of carbon disulfide were added at C. to the flask. The flask was cooled to 15 to 20C. Then 391 grams (2 mol) of benzotrichloride were added at temperatures of -15 to 20 C. over a period of 13 minutes. The flask was warmed to 0 to 5C. and held for 1 hour at which time 1 liter of methanol was added at 0 to 5C. followed by 500 ml. of water at the same temperatures. The mixture was heated and at 25C. steam was passed through until a temperature of 100C. was reached. The mixture was then cooled and poured into dilute hydrochloric acid and extracted with diethyl ether and dried over sodium sulfate. The solvent was stripped off and the residue was stripped and a fraction of 288.7 grams of 2- hydroxy-Sdodecylbenzophenone was recovered.

A solution of 70 grams of the 2-hydroxy-5-dodecylbenzophenone as prepared above in 60 ml. glacial acetic acid and 40 ml. acetic anhydride was charged to a 500 ml. round bottom flask equipped with a stirrer, thermometer and The above data show that the compounds of the present invention are highly effective copper extractants at very low pHs. In comparison, the corresponding 2-hydroxy-5-dodecylbenzophenoxime under equivalent conditions extracted 18 ppm copper at 0.02 pH, 180 ppm copper at 0.50 pH, and 1010 ppm copper at 0.96 pH. Thus compounds of the present in-' 10-0.05M NaHCOa I dropping funnel, and cooled by means of an ice bath to C. Ten milliliters of fuming nitric acid was added dropwise with stirring over a minute period at 2022C. Stirring was continued at 1520C. for an additional 20 minutes. The reaction mixture was poured into 200 m1. H 0 and the mixture extracted three times with diethyl ether. The ether solution was washed with water, 5 percent aqueous NaHCO and again with water. It was then dried over sodium sulfate and stripped of solvent to yield 76.1 grams of residue. Molecular distillation of 57.9 grams of this residue at 0.8 mm. Hg. and 210C. gave 55.3 gm. of product which was 2-hydroxy-3-nitro-5dodecylbenzophenone.

A mixture of 54.6 grams of 2-hydroxy-3nitro-5-dodecylbenzophenone as prepared above, 18.5 grams hydroxylamine hydrochloride, 23.2 grams anhydrous sodium acetate and 100 ml. absolute methanol was charged to a 250 ml. round bottom flask equipped with a stirrer and reflux condenser. The reaction mixture was refluxed for 16 hours and then poured into 300 ml. water and extracted three times with Skellysolve B (a normal hexane solvent). The organic solution was washed with water, 5 percent aqueous Nal-lCO and again with water. The hexane solvent was stripped from the product. There was thus obtained 55.4 grams of 2-hydroxy-3-nitro-5-dodecylbenzophenoxime.

2. Extraction of Copper Mixtures of 10 ml. portions of a 5 percent wt./vol. solution of 2-hydroxy-3nitro-5dodecylbenzophenoxime in kerosene (50 grams of reagent diluted to 1 liter with kerosene), 5 ml. portions of a 6 gram/liter Cu (as CuSO '5l-l O) aqueous solution and ml. of various aqueous acid or base solutions were shaken at ambient room temperature in 60 ml. separatory funnels for 10 minutes each. The layers were then separated and the organic phase was analyzed for copper and the pH of the aqueous phase was determined. The results are set forth in the following Table I.

TABLE I M1. M1. Final Cu org. Cu Ml. pH adjuster pH in org.

10 5 251.2M H1804 0.08 573 10 5 250.8M H2804 0.22 715 10 5 25-OAM H2804 0.49 970 10 5 250.04M H2504 1.62 1320 10 5 25-H2O 2. 15 1425 10 5 250.008M NnHCOa 2.52 1435 10 5 250.012M NuHCOa 2.95 1490 The above data show that the compounds of the present invention are not only excellent extractants for copper at very low pl-l's but in addition very selective. Thus the ratio of Cu extracted to Fe*"* at pH 0.50 is 151 and such ratio is still 27 at pH 2.12.

4. Stripping of Cu From Loaded Organic Phase Fifteen milliliter portions of a 5 percent wt./vol. solution of 2-hydroxy-3-nitro-5dodecylbenzophenoxime in kerosene as used in part 2 loaded with 1,540 ppm Cu were shaken for varying times with 5 ml. portions of 10 and 30 percent by weight H solutions. The phases were then separated, the organic analyzed for Cu and the percent Cu stripped calculated. Results are set forth in the following Table 111.

The above data indicate that even at an organiczaqueous phase ratio of 3:1 and short contact times, a substantial proportion of the Cu is stripped from the loaded organic phase.

EXAMPLE II 1. Preparation of a Mixture of 2-Hydroxy-3-nitro-4-isopropylbenzophenoxime and 2-Hydroxy-5-nitro-4-isopropylbenzophenoxime To a 500 ml. round bottom flask equipped with a stirrer, thermometer and condenser were charged 138 grams (1 mol) salicylic acid and V2 gram aluminum chloride. To this mixture was added 143 grams (1.2 mol) thionyl chloride and then the reactants were heated to 50C. for 2% hours with stirring. The excess thionyl chloride was removed at aspirator vacuum, the product cooled, and grams (1.5 mol) cumene added thereto.

Three hundred seventy five ml. nitrobenzene and 159.5 grams aluminum chloride were added with mixing to a 2 liter round bottom flask equipped with a stirrer, thermometer and dropping funnel. The said mixture was cooled to 5C. and then the above prepared acid chloride-cumene mixture was added slowly with stirring at 48C. over a 50 minute period. The resulting reaction mixture was slowly heated to 40C. over a 1 hour period, the stirring was continued at 40 for 2 hours and acid or base solutions were shaken at ambient room temperature in 60 ml. separatory funnels for 2 minutes each. The layers were then separated, the pH of the aqueous phase was determined and the aqueous phase was analyzed for copper then overnight (about 15 hours) at ambient room tempera- 5 content. The results are set forth in the following Table IV. ture. The mixture was poured onto about 750 grams ice and The above data shows that very good extraction is obtained 150 ml. cone. HCl, and chloroform was added. It was boiled at low pH values. In comparison, 2-hydroxy-4'-isopropyl- 15 minutes on a steam bath, cooled, the organic layer benzophenoxime under the same conditions gave 3.5 percent, separated and the aqueous layer extracted with CHCl The 27 percent and 40.6 percent extraction at 0.62 pH, 1.19 pH combined organic layer and CHCI extraction solution was 1 and 132 PH respectively.

TABLE IV Percent Cu Cu M1. M1. Final aq. extracorg. Cu++ Ml. pH adjuster pH g., l. tion 1 Extraction:

A--. 20 10 10-1M H2801 0.30 2. 52 20 B- 20 10 5-H20, 5-1M H soi 0.55 2.14 32 c 20 s- 0, 2-1M 11 0s. 0 87 1.70 46.4 D 20 10 10-.1M E 501 1.05 1.39 56 E 20 10 10-.1 NaHso. 1.23 1.26 60 F 2o 10 10-H o 1.33 1.06 66.4

1 Analysis of an extracted aqueous phase made up as F above showed 3.15 g./1. Cu++.

washed with water, 5 percent aqueous Na CO water, and then saturated aqueous NaCl. It was dried and stripped on a rotary evaporator. Distillation of the residue up to 105 at 26 mm. Hg. gave 472.5 grams of a nitrobenzene-cumene mixture. The residue weighed 186.5 grams. The residue consisting of from 70-90 percent of the desired 2-hydroxy-4'-isopropylbenzophenone was distilled through a 15 in. Vigreaux column. The main collected fraction at 165-l67C. and 2.25 mm. Hg was the desired product at substantially 100 percent purity.

A solution of 24 grams (0.1 mol) 2-hydroxy-4isopropy1- benzophenone as prepared above in 16 ml. glacial acetic acid and 12 ml. acetic anhydride was added to a 100 ml. round bottom flask equipped with a thermometer, dropping funnel and stirrer. The solution was cooled to 5C. by means of an ice bath and 6 ml. fuming nitric acid was added very slowly over a 50 minute period such that the temperature never rose past 10C. After the addition was complete, the ice bath was removed, and in 10 minutes, the reaction had exothermed to 57C. The cooling bath was returned and stirring at 20C. was continued for 40 minutes after which the reaction mixture was poured onto ice. The mixture was extracted three times with ether and the combined ether solutions were washed with water, 5 percent aqueous NaHCO water and saturated aqueous NaCl. The solution was then dried and stripped of ether giving 24.4 grams of a dark oil. This oil was molecularly distilled using pseudocumene as a heating liquid (168C). A tarry residue of 6.0 grams and a dark orange distillate (3.5 mm. Hg.) of 15.8 grams were obtained. Analysis of the distillate showed that it consisted mainly of a mixture of about 2 parts 2-hydroxy-3-nitro-4"isopropylbenzophenone and 1 part 2-hydroxy-5-nitro-4'-isopropylbenzophenone.

Fourteen and one half grams (0.051 mol) of the above mixture were combined with 22 grams (0.316 mol) hydroxylamine hydrochloride, 28 grams (0.342 mol) anhydrous sodium acetate and 130 ml. absolute methanol in a 500 ml. round bottom flask equipped with a condenser, thermometer and stirrer. The reaction mixture was stirred at 63C. overnight (about 16 hours) after which it was poured into 200 ml. water, cooled and extracted three times with ether. The ether extracts were washed with water to pH 5 and then with saturated aqueous NaCl. This was followed by drying and stripping off of the ether to yield 15.1 grams of a sticky yellow solid which was a mixture of the desired 3 and 5 nitro oximes.

2. Extraction of Copper Twenty milliliter portions of an approximately 5 percent wt./vol. solution of the mixture of nitro oximes as above prepared in 1,1,2-trichloroethane (15 grams oxime and 285 ml. solvent), 10 ml. portions of a 6.35 gram/liter Cu (as CuSO,-5H O) aqueous solution having a pH OF 1.90 (obtained by adding conc. H 80 and 10 ml. of various aqueous EXAMPLE ll] 1. Preparation of a Mixture of 2-Hydroxy-3-nitro-4- dodecylbenzophenoxime and 2-l-lydroxy-5-nitro-4'-dodecylbenzophenoxime One hundred thirty eight grams (1 mol) salicylic acid, 143 (1.2 mol) grams thionyl chloride and 0.25 gram aluminum chloride were combined in a 500 ml. round bottom flask equipped with a stirrer, condenser and thermometer. This reaction mixture was heated to 50C. for 4.5 hours and then aspirator vacuum was applied to remove excess SOCI After cooling, 356 grams (1.5 mole) dodecyl benzene (Neolene 400--the dodecyl groups are straight chain alkyl) were added and the mixture allowed to stand overnight. With cooling, 160 grams (1.2 mol) aluminum chloride were added to 375 ml. nitrobenzene in a 2 liter round bottom flask equipped with a thermometer, stirrer and dropping funnel. Such mixture was cooled to 50C. and the above acid chloride-dodecylbenzene mixture added at 58C. over a 45 minute period. The resulting reaction mixture was slowly heated to 40C. over a 2 hour period, stirred an additional 4 hours at such temperature and then overnight (about 16 hours) at ambient room temperature. It was then poured onto 500 grams ice, 150 ml. conc. HCl was added with stirring and the mixture was heated 20 minutes on a steam bath. The cooled mixture was extracted three times with ether, the combined ether extracts were washed with water to pH 3.5, then with 5 percent aqueous NaHCO water and finally with saturated aqueous NaCl (three times). It was dried and stripped of ether giving 854 grams of a dark oil. Distillation at 24 mm. Hg. up to 116C. gave 446 grams red distillate and 389 grams residue. The residue was distilled through a 10 in. Vigreaux column to yield an 84 gram fraction at l75195C. and 0.1 mm. Hg. which analyzed nearly 70 percent 2 -hydroxy-4"dodecylbenzophenone.

The above fraction along with 40 ml. glacial acetic acid and 30 ml. acetic anhydride were added to a 500 m1. round bottom flask equipped with a stirrer, thermometer, condenser and dropping funnel. The mixture was cooled to 5C. and 1 1 m1. of fuming nitric acid was added with rapid stirring over a 45 minute period while maintaining the temperature at 5-7C. After an additional 15 minutes at 7C., the reaction mixture was poured onto grams ice and extracted three times with ether. The combined ether extracts were washed with water to pH 4 and then with 5 percent aqueous NaHCO An emulsion formed so 10 percent aqueous HCl was added and the ether solution again washed with water to pH 4. This was followed by three washings with saturated aqueous NaCl after which the extract solution was dried. The ether was vacuum stripped yielding 108.2 grams of a dark oil. The product consisted of about 50 percent of a mixture of 2-hydroxy-5-nitro-4- dodecylbenzophenone and 2-hydroxy-3-nitro-4'-dodecylbenzophenone in a ratio of approximately 2: 1.

Thirty eight grams of a mixture of the compounds as washed with water to pH 3, 3 times with 5 percent aqueous Nal-lCO water and saturated aqueous NaCl. It was dried and stripped of solvent and predistilled to yield a residue weighing 514.0 grams. This residue was distilled through a 30 in.

prepared above, 12.9 grams hydroxylamine hydrochloride, 5 Vigreaux column to yield several fractions including an 86.5 16.1 grams anhydrous sodium acetate and 85 ml. absolute gram fraction at 045-07 mm. Hg, pot temperature of methanol were combined in a 250 ml. round bottom fla k 274288C. and vapor temperature of 2l0217C. Analysis equipped with a stirrer, thermometer and condenser. The mixshowed that this fraction consisted of 68 percent of 2-hydr0xture was refluxed overnight, poured into water and extracted 1 y y p with Skellysolve B. The Skellysolve B layer, upon standing To a 500 round bottom flask Were addeel 75 grams 9 over a weekend, had a layer of insolubles in it. Water washing the benlophenone t P p e e, g i l acetic removed the insolubles, the same being suspended i h acid and 75 ml. acetic anhydr1de.Th1s mixture was cooled to aqueous layer. The Skellysolve B phase was again washed with about f 9- f fungmg nlmc 1 was added water, 5 percent aqueous NaHCO and saturated aqueous Over a 10 mmute P P at 13 The g bath was N c1 I was i d d i d f Solvent to yield 323 grams removed and the reaction slowly exothermed to 32 C. over 10 f he i d 3 d 5 nitro oxime product minutes. The mixture was then poured onto ice and extracted 2. Copper Extraction with Skellysolve B. The organic layer was washed with water, A 5 percent wt./v0l. solution of the mixed oxime prepared 5 p r n q H n w t saturated aqueous l, in part 1 in kerosene was used to extract copper from various 20 dried and PP of Solvent glvmg grams of a dark aqueous solutions also containing The extractions were Molecular distillation at 0.2 mm. Hg. using aniline as the heatcarried out for 10 minutes at ambient room temperature in 60 g m m 8 a esidue y of i and a distilml. se a ator f nnel Th fi l or ilib i H was d late in two fractions: 42.5 grams and 12.0 grams. Both fracmined and the loaded organic phases were analyzed for Cu tions consisted essentially of 2-hydroxy-3-methyl-5-n1tro-4- and F e***. The results are set forth in the following Table V. dodecylbenzophenone- TABLE V Aqueous, ml.

C F Org. Cu++ Fe+++ Final p.p.m. ppm. Extraction r111. sol sol. Additive pH org. org.

10 5 5 20-1120 1.82 2,100 143 10 5 5 $111 NaHcoi 15Hg0 2 22 2,115 155 10 5 5 20-.111 H2801 1.30 1, 790 90 10 5 5 5-21 H3804 15-11 0 0.40 888 40 10 5 5 10-2M11ps0i 10wator 0 08 615 l The copper solution contained 5.95 g. 511:0 with water). The Fe+++ solution 29.28 grams Fe2 s04 TXH20 w the various additive solutions.

EXAMPLE 1V 1. Preparation of 2-l-lydroxy-3methyl-5-nitro-4-dodecylbenzophenoxirne Three hundred four grams (2 mol) of 3-methyl salicylic acid, 225 ml. (3.1 mol) thionyl chloride and /2 gram AlCl were combined in a 2 liter round bottom flask and stirred while heating from 25C. to 50C. over a 2 /2 hour period. Stir ring at 50C. was continued for 2 more hours and then aspirator vacuum was applied to remove the excess SOCl To the residue was added 845 ml. (729 grams, 3 mol) of dodecyl benzene (AB 515 available from Conoco--the dodecyl groups are random-branched alkyl groups).

Seven hundred fifty ml. nitrobenzene was charged to a 5 liter round bottom flask and then 333 grams (2.5 mol) aluminum chloride were added thereto with cooling and stirring. When this mixture reached 10C., the above dodecyl benzeneacid chloride combination was added over 20 minutes by a dropping funnel. Then the reaction mixture was slowly heated /l. Cu++ (prepared by diluting 23.58 grams Ju$ 0;- contained 6.64 g./l. Fe+++ (prepared by dilutmg ith Water). The aqueous phases were made up to 30 ml. by

Fifty-two grams of the above-prepared benzophenone were combined with 18.0 grams hydroxylamine hydrochloride, 22.4 grams anhydrous sodium acetate and 1 10 ml. absolute methanol in a 250 ml. round bottom flask and stirred under reflux overnight. The reaction mixture was poured into 200 ml. water and extracted three times with Skellysolve B. After standing a few minutes, a bulky precipitate formed in the organic extractant. It dissolved upon the addition of a small amount of ether. The organic phase was then washed with water, 5 percent aqueous NaHCO water, saturated aqueous NaCl, dried and stripped of solvent giving 53.3 grams semisolid product consisting of about 90 percent of 2-hydroxy-3- methyl-5-nitro-4-dodecylbenzophenoxime and about 10 percent of the starting benzophenone.

2. Copper Extraction Part 2 of Example III was essentially repeated except that 2- hydroxy-3-methyl-5-nitro-4-dodecylbenzophenoxime was used as the extractant. The results are set forth in the following Table VI.

over 2 hours to 40C., maintained at 40C. for 4 hours and stirred at room temperature overnight. The reaction mixture was then poured onto about 600 gm. of ice and 300 ml. conc. HCl and stirred in a steam bath for /2 hour. It was then extracted 3 times with Skellysolve B and the organic layer The compounds of the present invention can also be used in combination with other extractants where desired and, in particular, with certain a-hydroxy aliphatic oximes. The latter compounds can further improve the kinetics of the extraction at low pl-ls without any serious effect on the selectivity of the where R, R and R may be any of a variety of organic radicals such as aliphatic and alkylaryl radicals. R may also be hydrogen. Preferably, R and R are unsaturated hydrocarbon or branched chain alkyl groups containing from about 6 to carbon atoms. R and R are also preferably the same and when alkyl are preferably attached to the carbons substituted with the -OH and NOH groups through a secondary carbon atom. It is also preferred that R is hydrogen or unsaturated hydrocarbon or branched chain alkyl groups containing from about six to 20 carbon atoms. The a-hydroxy oximes also preferably contain a total of about 14 to 40 carbon atoms. Representative compounds are l9-hydroxyhexatriaconta- 9 ,27-dienl 8-oxime, 5,10-di-ethyl-8-hydroxytetradecan-Y-oxime, and 5,8-diethyl-7-hydroxydodecane-6-oxime. The later compound has the following structural formula:

i on: OH NOH H Representative of other monoand polyunsaturated radicals are heptenyl, octenyl, decenyl, octadecenyl, octadecynyl and alkyl substituted radicals such as ethyloctadecenyl. Representative of other monoand polyalkyl substituted saturated radicals are ethylhexyl, diethylheptyl, butyldecyl, butylhexadecyl, ethylbutyldodecyl, butylcyclohexyl and the like. The R, R and R' groups may contain inert substituents.

The a-hydroxy oxime extractants are also characterized as having a solubility of at least 2 percent by weight in the waterimmiscible organic solvent used to make up the organic phase and substantially complete insolubility in water. In addition, it is believed that the copper values and the a-hydroxy oxime extractant form a complex during the initial extraction step and such complex, when formed, should also have a solubility of at least 2 percent by weight in the hydrocarbon solvent.

The relative amounts of the compounds of the present invention and the said a-hydroxy aliphatic oximes can be varied widely. Even minute quantities of the a-hydroxy aliphatic oxime can be beneficial. However, a preferred range is l to 100 percent by weight of the ochydroxy aliphatic oxime based on the weight of the compounds of the present invention, with an especially preferred range being 15-50 percent by weight. In general, the concentration of total oxime is in the range of about 2-25 percent, based on the weight of the organic extracting solution.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for the recovery of copper values from an acidic aqueous solution comprising: (i) contacting said aqueous solution with an organic phase comprising a liquid, essentially water-immiscible organic solvent and a sufficient amount of a substituted 2-hydroxybenzophenoxime to extract at least a portion of the copper values into the organic phase, (2) separating the resultant copper-pregnant organic phase from the aqueous phase, and (3) recovering copper values from the organic phase, said aqueous solution having an equilibrium pH of less than about 1.5 after the contacting with the organic phase, and said substituted 2-hydroxybenzophenoxime; (a) having the formula in which R and R may be individually alike or different and are saturated aliphatic groups of one to 25 carbon atoms, ethylenically unsaturated aliphatic groups of three to 25 carbon atoms or OR" where R" is a saturated or ethylenically unsaturated aliphatic group as defined, E is an electron withdrawing substituent, p is l, 2, 3 or 4, m is 0 or a whole integer up to 4-p, n is O, l, 2, 3 or 4, R," and R' contain a total of three to 25 carbon atoms and the electron withdrawing substituent E substantially increases the efficiency of the compound as a copper extractant from aqueous solutions having a pH of less than about 1.0; and (b) being further characterized as being essentially insoluble in water and having a solubility of at least about 2 percent by weight in an essentially water immiscible organic solvent.

2. A process according to claim 1 in which the copper values are stripped from the organic phase by means of an acid.

3. A process according to claim 2 in which the acid is sulfuric acid.

4. A process according to claim 1 in which the acidic aqueous solution has an equilibrium pH of less than about 1.0 after the contacting with the organic phase.

5. A process according to claim 1 in which the essentially water-immiscible organic solvent is a liquid hydrocarbon.

6. A process according to claim 5 in which the liquid hydrocarbon is kerosene.

7. A process according to claim 1 in which the organic phase contains about 2 to 50 percent by weight of the substituted 2-hydroxybenzophenoxime.

8. A process according to claim 1 in which R is an unsubstituted branched chain aliphatic hydrocarbon group.

9. A process according to claim 1 in which R is an unsubstituted branched chain aliphatic hydrocarbon group.

10. A process according to claim 1 in which the electron withdrawing substituent is a nitro group.

11. A process according to claim 1 in which the acidic aqueous solution has an e uilibriurn pH of less than about 1.0 after the contacting with t e organic phase, the essentlally waterimmiscible organic solvent is kerosene, the substituted 2- hydroxybenzophenoxime is used in an amount of about 5 to 15 percent based on the weight of the organic phase, the substituted Z-hydroxybenzophenoxime is 2-hydroxy-3-nitro-5- dodecylbenzophenoxime and the copper values are stripped from the copper-pregnant organic phase by means of sulfuric acid.

12. A process according to claim 1 in which the organic phase also contains an a-hydroxy aliphatic oxime having a solubility of at least about 2 percent by weight in the essentially water-immiscible organic solvent and having the formula where R and R are organic radicals and R is selected from the group consisting of hydrogen and organic radicals.

13. A process according to claim 12 in which the a-hydroxy aliphatic oxime is employed in a proportion of l to percent by weight based on the weight of the substituted 2- hydroxy-benzophenoxime.

14. A process according to claim 1 in which E of the formula is a chloro group in the ortho position to the hydroxyl group.

TED STATES PATENT OFFECE (IE'HFMATE 0F (IOCHN Patent No. 3 558%? Dated April 11, 1972 lnventofls) Phillip L. Mattison, Ronald R. Swanson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 12, "reactants" should read extractants line 7 L, after "are" insert as Column 8, line 5,

TABLE IV should be inserted between paragraph ending "following Table IV." and paragraph beginning "The above data ."g

in TABLE IV, after "Extraction C" the M1. pH adjuster should read 8-H O, 2-1M H SO line 42, "50C should read 5C. Column ll, line 16, "NOH" should read =NOH Column 12, lines 56-62, the formula should read OH NOH n 2 R c c R Signed and sealed this 10th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCI-LER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

2. A process according to claim 1 in which the copper values are stripped from the organic phase by means of an acid.
 3. A process according to claim 2 in which the acid is sulfuric acid.
 4. A process according to claim 1 in which the acidic aqueous solution has an equilibrium pH of less than about 1.0 after the contacting with the organic phase.
 5. A process according to claim 1 in which the essentially water-immiscible organic solvent is a liquid hydrocarbon.
 6. A process according to claim 5 in which the liquid hydrocarbon is kerosene.
 7. A process according to claim 1 in which the organic phase contains about 2 to 50 percent by weight of the substituted 2-hydroxybenzophenoxime.
 8. A process according to claim 1 in which R is an unsubstituted branched chain aliphatic hydrocarbon group.
 9. A process according to claim 1 in which R'' is an unsubstituted branched chain aliphatic hydrocarbon group.
 10. A process according to claim 1 in which the electron withdrawing substituent is a nitro group.
 11. A process according to claim 1 in which the acidic aqueous solution has an equilibrium pH of less than about 1.0 after the contacting with the organic phase, the essentially water-immiscible organic solvent is kerosene, the substituted 2-hydroxybenzophenoxime is used in an amount of about 5 to 15 percent based on the weight of the organic phase, the substituted 2-hydroxybenzophenoxime is 2-hydroxy-3-nitro-5-dodecylbenzophenoxime and the copper values are stripped from the copper-pregnant organic phase by means of sulfuric acid.
 12. A process according to claim 1 in which the organic phase also contains an Alpha -hydroxy aliphatic oxime having a solubility of at least about 2 percent by weight in the essentially water-immiscible organic solvent and having the formula where R1 and R2 are organic radicals and R3 is selected from the group consisting of hydrogen and organic radicals.
 13. A process according to claim 12 in which the Alpha -hydroxy aliphatic oxime is employed in a proportion of 1 to 100 percent by weight based on the weight of the substituted 2-hydroxy-benzophenoxime.
 14. A process according to claim 1 in which E of the formula is a chloro group in the ortho position to the hydroxyl group. 